<!DOCTYPE html>
<html lang="zh-cn">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>直接相邻选择器</title>
    <style>
        #two+p {
            color: greenyellow;
            background-color: grey;
            font-size: 30px;
        }
    </style>
</head>

<body>
    <span>
    <p>老大</p>
    <p id="two">老二</p>
    <p>老三</p>
    <p>老四</p>
</span>
</body>

</html>